Locking apparatus operable for releasably locking together two relatively movable members are well known. Such apparatus can generally be divided into two categories, those providing an automatic unlocking capability in the unlocking mode, and those that provide an automatic locking capability when in a locking mode. Reference as an example in this first regard, Hogan U.S. Pat. No. 4,217,064, issued Aug. 12, 1980, to Spectrum X-Ray Corporation, which discloses a latching mechanism incorporating a pivotal cam operable in a locking position for driving a spring loaded plunger into a receiver for holding two members together. In this mechanism, the spring urges the plunger from the receiver when the cam is moved to an unlock position, to allow the members to be relatively moved. However, the spring loaded plunger must be aligned with the receiver for the cam to be moved to the locking position. Thus, no automatic locking capability is provided.
Reference in the second regard, Jermyn, Jr. U.S. Pat. No. 6,065,896, issued May 23, 2000 to the United States of America, which discloses a lever device having an automatic locking capability when in a locking mode. However, no mechanism is provided for automatically unlocking the device when in an unlock mode.
Here, what is meant by an automatic unlocking capability in an unlocking mode is for the locking apparatus to automatically release or disengage the relatively movable members to allow the relative movement thereof, when or after the apparatus is actuated or moved to an unlocking mode, such as by actuation or movement of an actuating element such as a lever, latch, or the like. What is meant by an automatic locking capability when in a locking mode is to lock the members together when in a selected predetermined relative position when or after the apparatus is actuated or moved to a locking mode by actuation or movement of the actuating element.
There are numerous applications in which it would be advantageous to have a locking apparatus which provides both an automatic locking capability when actuated or moved to an unlocking mode, and an automatic locking capability when moved to a locking mode. As an example, a crop residue spreader is often supported on a rear end of an agricultural combine for movement between one or more operating positions, and a service or access position. Such spreaders are typically relatively heavy devices and require locking apparatus on two sides thereof to be releasably supported in a selected position. Reference in this regard, Wolters et al. U.S. Application Publication No. U.S. 2003/0114207A1, published Jun. 19, 2003, which discloses a multi-position linkage and locking mechanism adapted for such application. This mechanism utilizes spring loaded pins receivable in holes at different locations on a supporting structure when the spreader is moved to one or more predetermined positions, for releasably holding the spreader in the position. To release the spreader, a release bar is moved to a release position to pull the pins from the holes in opposition to the springs. However, in some positions, a substantial portion of the weight of the spreader can be acting to hold the pins in the holes, such that to release the spreader, both the spring forces acting to hold the pins in the holes and the portion of the weight of the spreader acting on the pins must be simultaneously overcome.
Thus, what is sought is a locking apparatus adapted for releasably holding a relatively heavy device such as a crop residue spreader or the like, which is actuatable or movable into an unlocking mode so as to automatically unlock when any forces urging the apparatus to remain in the locked condition are overcome or removed, and when actuated or moved into a locking mode, will automatically lock when the heavy device is moved in a predetermined manner and/or to a predetermined position.